CFD analysis of paramagnetic particle containment in microwells

Designs for a flow-through biochemical sensor based on rotating chains of paramagnetic particles are analyzed with computational fluid dynamics and theoretical relations for particles in fluids. The sensor is based on the behaviour of paramagnetic particles-in particular, their tendency to align themselves into chain-like structures when subjected to a magnetic field. Paramagnetic particles can be prepared onto which fluorescently tagged analytes will attach. Rotating magnetic fields rotate the particle chains providing the opportunity to selectively acquire the signal associated with chains, through well known lock-in amplifier techniques. Commercially available CFD software can be used to address some basic questions in the design of such a sensor. Computational and experimental results suggest that a trade-off exists between the efficiency of delivering the analyte to the particle chains and the difficulty of holding the chains in the desired location.